16 University of Michigaii 



Salinja van Sint Michiel, is considerably lower (51.2 meters) 

 than Seroe Blandan across the lagoon, the western escarp- 

 ment is more heavily wooded and has a richer molluscan 

 fauna. 



Station C9. Seroe Popchie (9-E; L69° 3.92', 12° 12.44'). 

 This hill of the older limestone (85.3 meters) on the eastern 

 side of Boca Sint Marie (9-G) is quite barren, as regards 

 both vegetation and molluscan population. The collection 

 comes from the steep, western slope. 



Station CIO. Seroe Boca (10-H; L68° 49.19', 12° 7.14'). 

 This low ridge (40 meters) on the eastern side of Sint Joris 

 Baai (lO-I) is one of the most barren localities collected. The 

 cap of older limestone is quite thin and the reddish residuum 

 correspondingly prominent. The top of the mesa is quite 

 devoid of vegetation, with the exception of two or three giant 

 cacti (Cereus). The trade winds, although they come fresh 

 from the ocean, are so dry that after a few hours sojourn 

 (much of the time in the shade), my conjunctivae became 

 so inflamed that I was hardly able to see for some time after- 

 ward. However, the deeper crevices of the rocks are green 

 with grass, and dwarfed manzalienja trees, which require 

 considerable moisture, are bunched on the leeward side of the 

 escarpments and detached rocks. The effect of the trades is 

 evident, for their tops are leveled off at the limit of protec- 

 tion, as if they had been trimmed artificially. The entire 

 aspect of the locality gives the impression of a wind-swept 

 mountain peak at and above timberline (compare fig. v-11). 

 As already mentioned, I suspect that a portion of the moisture 

 comes from the heavy dews; I am sure that these form in 

 similar places on Aruba. Despite the vicissitudes of such a 

 habitat, Tudora and Cerion are present in the cracks of the 

 rocks and even upon the cacti. Peculiarly enough, the speci- 

 mens of the former are larger than the average, although 

 those of the latter are much dwarfed (C uva diahlensis) . The 

 specimens of Cerion from the base of the leeward escarp- 

 ment, where they occur even under the manzalienjas, are 

 larger than those from the summit of the ridge ; the entire lot 

 from this station gives a bimodal curve. 



